The present invention generally relates torch igniters for initiating a combustion event in devices such as industrial burners or combustors for gas turbine engines, ramjets or combined-cycle engines and more particularly to a torch igniter having increased mass flux and energy.
Conventional aircraft engines, ramjets, combined-cycle engines and industrial burners typically include an electronically actuated ignition source for initiating a combustion event in a combustion chamber. Such electronically actuated ignition sources are usually of the spark igniter type or the plasma jet type.
Spark igniters typically utilize a spark plug-like device for generating a discharge arc which is employed to generate a flame kernel that ignites a mixture of fuel and oxidizer (e.g., air or oxygen) in the combustion chamber. Plasma jet igniters typically employ a fuel source, such as hydrogen or jet fuel, that dissociates in a spark discharge to produce a kernel of various radicals that in turn initiate a combustion event in the combustion chamber.
If the rate of heat loss from the kernel is less than the rate of heat production in the kernel, the ignition front advances leading to combustor light-off. Most conventional igniters require favorable aerodynamic conditions to advance the ignition front. Some combustors, however, are engineered to operate with inlet conditions (e.g., during supersonic pre-ignition flow) and/or fuel conditions (e.g., fuel type, fuel droplet size, the extent to which the fuel and air have mixed) that do not present the favorable aerodynamic conditions that are necessary for reliable ignition and flame propagation with conventional igniters. Further aggravating this situation, it may not be practical to place the igniter relative to the combustor in the position where it would be most effective as when, for example, the placement of the igniter is dictated by concerns for serviceability or the packaging of the combustor into an application. Accordingly, there remains a need in the art for an improved igniter.
In one preferred form, the present invention provides a torch igniter having a housing and an electronic ignition source. The housing defines a combustion chamber, at least one fuel conduit and at least one oxidizer conduit. The fuel conduit or conduits intersect the combustion chamber forwardly of an end wall and are configured to dispense at least one stream of fuel into the combustion chamber. The oxidizer conduit or conduits intersect the combustion chamber forwardly of the end wall and are configured to dispense at least one stream of oxidizer into the combustion chamber. The streams of fuel and oxidizer mix to produce a fuel/oxidizer mixture. The fuel and oxidizer conduits are positioned relative to the combustion chamber so as to create an upstream recirculation zone and a downstream recirculation zone that stabilize and pilot combustion within the combustion chamber. The electronic ignition source is coupled to the housing and generates a kernel that is dispensed into the combustion chamber rearwardly of the fuel and oxidizer conduits. The kernel initially ignites the fuel/oxidizer mixture in the recirculation zone, which propagates throughout the combustion chamber.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.